Frana Allen [Skinner Elementary
Matter and Atoms
Frana passed around several sheets relating to atomic structure. We began by reviewing information on matter [solid-liquid-gas, mass, density, atoms], focusing on the chemical elements:
Frana showed the positions of various elements on the Periodic Table [see the WebElements website: http://www.webelements.com/]. As an example, the element Potassium [found in bananas -- its symbol K comes from its Latin name Kalium] contains P = 19 protons and N = 20 neutrons in its nucleus. Its atomic number Z is equal to the number of protons in the nucleus: Z = P. Its atomic mass, A = P + N, is given by the total number of protons and neutrons in the nucleus of the atom in question. For Potassium the numbers are Z=20 and A = 39, written as: 19K39.
Frana pointed out that electron orbits are arranged in various types of shells, with each shell holding a certain maximum number of electrons:
|Shell Symbol||Maximum Number
of Electrons Allowed
Pat Riley [Lincoln Park HS, Chemistry] pointed out that this simple electronic structure becomes more complicated beyond Z=20 [calcium: Ca], in that D shells begin to contain electrons, and the order of filling electronic shells becomes more complicated. The filling sequence is as follows:
Using the lovely template distributed by Frana [to see it click here], we determined and studied the structure of the chemical elements for atomic numbers Z= 1 [Hydrogen H] through Z=9 [Fluorine: F].
We learned a lot about atomic structure today. Nicely done, Frana!
Chris Etapa [Gunsaulus Academy]
Forces and Motion
/ Cars and Hovercrafts
Chris presented an activity described on the Look · Learn and Do Publications website: http://www.looklearnanddo.com. Chris successfully used the lesson contained there in her eighth grade class. First, Chris reviewed the meanings of the terms distance, velocity, and acceleration. Using boxes equipped with primitive, home-made wheels, the class was divided into groups of 4, and each group designed and built a car. Next, the students tested their cars by giving them a push and measuring the distance D traveled over a given time interval T. They then calculated the velocity V = D / T. This completed the activities described on that webpage.
Next, her students made hovercrafts from one liter water bottles and balloons --- an activity based upon previous SMILE miniteach presentations [ph8901.html; pl95m7.html]. We did a variation of this activity during today's class.
After dividing into groups of 3-4 participants, we stood the bottle vertically on its base, and cut around the top portion of the bottle at its shoulder, forming an inverted cup-like structure. We stretched the lip of the balloon over opening of the bottle, with the cap removed, and blew into the opening at the shoulder, inflating the balloon. When the balloon was inflated we held the air in it by pinching it just above the cup. We set the apparatus upright on the table, with the shoulder rim resting on the flat surface, and released the pinch. The air rushed out of the balloon, into the inverted bottle-cup, and out at the shoulder opening or rim, and the hovercraft rose slightly off the table. In fact, the craft began to move slightly across the table --- presumably because of residual asymmetries. Ken Schug modified the apparatus by taking the plastic bottle cap, punched a small hole in its center, and then put it on the bottle-cup. When the balloon was re-attached, re-inflated, and released the outflow of air into the room was reduced, and the motion of the bottle was more stable. This modification was suggested by Larry Alofs [Kenwood HS, physics], a visitor from the Math-Physics SMILE program.
Questions to ask:
Fred Schaal [Lane Tech HS,
Physics] Tree Circumferences
Fred described measuring the circumference c (in inches) of a tree (with roughly circular cross section) in order to determine its diameter d (in inches), by dividing by p » 22/7 (or, better yet, p » 355/113):
Fred also reported data on the Christmas Bird Count:
|species||Percentage of decline|
|blue jays||60 %|
You helped us get around a difficult subject which is not just for the birds! Interesting, Fred.
Notes taken by Ben Stark.